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NEET BIOLOGYMedium

Select the two correct statements out of the four (a-d) given below about lac operon: (a) Glucose or galactose may bind with the repressor and inactivate it. (b) In the absence of lactose, the repressor binds with the operator region. (c) The z-gene codes for permease. (d) This was elucidated by Francois Jacob and Jacques Monod.

A

(b) and (c)

B

(a) and (c)

C

(b) and (d)

D

(a) and (b)

Step-by-Step Solution

According to the NCERT text:

  1. Statement (a) is incorrect: Glucose or galactose cannot act as inducers; lactose or allolactose binds to the repressor to inactivate it .
  2. Statement (b) is correct: In the absence of lactose (inducer), the repressor protein binds to the operator region of the operon and prevents RNA polymerase from transcribing the operon .
  3. Statement (c) is incorrect: The z-gene codes for beta-galactosidase, while the y-gene codes for permease .
  4. Statement (d) is correct: The lac operon was elucidated by Francois Jacob and Jacque Monod . Therefore, statements (b) and (d) are correct.
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